Embodiments of the invention relate generally to diagnostic imaging and, more particularly, to an apparatus and method of visualizing features in an image.
Typically, imaging systems produce two- or three-dimensional images that are made available to a practitioner for visualization. Such applications include but are not limited to computed tomography (CT) and magnetic resonance (MR). These systems include applications that may be used to examine and identify elements based on their atomic number, tissue, bone, bone and calcifications within a body, and they may be used to determine a wall thickness in a canal or passageway, as examples. These applications may be enhanced by the use of contrast agents.
In CT imaging systems, an x-ray source emits a fan-shaped or cone-shaped beam toward a subject or object, such as a patient or a piece of luggage. The CT imaging system may include a conventional scintillator-based third-generation CT system, or may include an energy sensitive (ES), multi-energy (ME), and/or dual-energy (DE) CT imaging system that may be referred to as an ESCT, MECT, and/or DECT imaging system, in order to acquire data for material decomposition or effective Z or monochromatic image estimation. The beam, after being attenuated by the subject, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is typically dependent upon the attenuation of the x-ray beam by the subject. Each detector element of the detector array produces a separate electrical signal indicative of the attenuated beam received by each detector element. The electrical signals are transmitted to a data processing system for analysis, which ultimately produces multiple two-dimensional slices or three-dimensional image reconstructions that may be accessed by a practitioner.
In MR systems, when a substance such as human tissue is subjected to a uniform magnetic field (polarizing field B0), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency. If the substance, or tissue, is subjected to a magnetic field (excitation field B1) which is in the x-y plane and which is near the Larmor frequency, the net aligned moment, or “longitudinal magnetization”, MZ, may be rotated, or “tipped”, into the x-y plane to produce a net transverse magnetic moment Mt. A signal is emitted by the excited spins after the excitation signal B1 is terminated and this signal may be received by a detector and processed to form multiple two-dimensional images or three-dimensional image reconstructions that may be accessed by a practitioner.
Thus, imaging systems and applications are available that have the capability to greatly enhance and improve the diagnostic capabilities of a medical practitioner. Images rendered are typically in the form of three-dimensional (3D) blocks, or slices, that may be viewed by a practitioner, and the imaging data may be useful for visualization of the human body for clinical purposes related to medical procedures and diagnosis of disease. Such imaging applications, though, can create a surplus of information for a medical practitioner to evaluate, and the challenge is more acute for wide coverage of anatomical areas. Thus, while imaging capabilities have been greatly increased in recent years (i.e., resolution, speed, coverage), it is desirable to be able to efficiently sort through the abundance of information and pinpoint areas that are of most interest to the practitioner.
As is known in the art, there are numerous methods for visualization of large 3D imaging data sets, including rendered images, color coded images, and minimum or maximum intensity projection (MIN IP/MIP). However, though these methods may yield a high resolution image to aid in diagnosis of a condition, such techniques may not allow a practitioner to quickly review images and focus on those aspects of the image that may be most important to a diagnosis. For instance, parameters that may be of interest in a medical image may include a plaque thickness in a vessel or a wall thickness in an airway. Typically, the image may be virtually rotated to observe features of the structure that may be of interest, such as plaque, wall thickness in an airway, etc. Plots of measured parameters along a vessel or plots of average wall thickness of a vessel may be generated, as examples. However, such plots tend to be time-consuming to analyze, may be difficult to interpret, or may mask or hide irregularities in the image. Thus, even though an image may actually contain data of interest to aid in diagnosis of a condition, such data may be overlooked due to a lack of time or resources.
Therefore, it would be desirable to improve visualization techniques in three-dimensional images.